Abstract: A hairbrush for people and pets is provided that releases perfume, oils, fragrance, or other active compositions when brushed. The hairbrush includes a flexible and selectively deflectable bladder that is deformed when bristles interconnected thereto are moved. Bladder deformation causes air exposed to a scent-producing element positioned within the bladder to be expelled. Removal of external pressures from the bladder causes and ambient air to be captured and scented.

Abstract: In vivo measurement of the concentration of a substance in the blood, e.g. glucose, despite varying concentrations of interfering components, e.g. protein and fat, by measuring the absorption of infra red light at a pair of selected wavelengths in the range 1-40 .mu.m for each of the substance and the components one being a measuring wavelength at which the substance or component show a specific absorption and another being a reference wavelength at which the substance or component shows a low absorption, at least one wavelength being selected from the range 1-10 .mu.m. The absorption is measured using a detector providing a computable electric signal corresponding to the absorbed amount of infra red radiation at the respective wavelengths. The electric signals are used to calculate the concentration of the substance taking into account the absorption caused by the interfering components.